const kk = Symbol('kk')
const obj = {[kk]:'9',6:'6',0:'abc','a':'6666',7:"7"}
console.log(obj,'obj')
console.log(Reflect.ownKeys(obj))


//如果map的key相同，后者会覆盖前者
const obj1 = new Map()
const a = {id:1}
obj1.set('1',{a:1})
obj1.set(a,{a:1})
obj1.set(a,{a:1})
console.log(obj1.get('1'))

// obj1.clear()
console.log(obj1.size)
console.log(obj1,'obj1')
console.log(obj1.has('1'))
console.log([...obj1.keys()])
console.log([...obj1.values()])


let key = {a:1}
const wek = new WeakMap()
console.log(wek.has(key),'wek0')
wek.set(key,{a:123})
// key = null
console.log(wek.get(key),'wek1')

